The Fukushima Daiichi Nuclear Accident: Final Report of the AESJ Investigation Committee

566 Pages·2015·10.23 MB·English

by  Atomic Energy Society of Japan (eds.)

The Fukushima
Daiichi Nuclear
Accident
Final Report of the AESJ Investigation
Committee
The Fukushima Daiichi Nuclear Accident

Atomic Energy Society of Japan
Editor
The Fukushima Daiichi
Nuclear Accident
Final Report of the AESJ Investigation
Committee
Editor
AtomicEnergySocietyofJapan
Tokyo,Japan
OriginalJapaneseedition
TheFukushimaDaiichiNuclearAccident-FinalReportoftheAESJInvestigation
CommitteeByAtomicEnergySocietyofJapan,Copyright©2014Publishedby
MaruzenPublishingCo.,Ltd.
2-17KandaJimbo-cho,Chiyoda-ku,Tokyo,Japan
ISBN978-4-431-55159-1 ISBN978-4-431-55160-7(eBook)
DOI10.1007/978-4-431-55160-7
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Preface
OnMarch11,2011,theaccidentattheFukushimaDaiichiNuclearPowerStations
of Tokyo Electric Power Company occurred by the Great East Japan Earthquake
induced the worst case scenario of releasing a massive amount of radioactive
materials, causing the devastating effects of nuclear disasters to make known to
the world. Even now, after three and a half years have passed since the accident,
manypeopleareforcedtoliveoutsidetheevacuationareaandthistellshowdeep
the ravages of the accident have left behind. And still, the decommissioning of
nuclearpowerreactorshasmanytoughchallenges,includingsuchasthetreatment
ofcontaminatedwaterandunloadingofmoltenfuels.
TheAtomicEnergy Society ofJapan (AESJ)feels thestrongresponsibilityfor
the nuclear disaster of this kind as a nuclear science/engineering specialist group,
and since the accident, we have been actively involved in a convergence of the
accidentandarestorationofthesurroundingenvironment.
As a part of this effort, the “AESJ Investigation Committee on the Accident at
theFukushimaDaiichiNuclearPowerStationofTokyoElectricPowerCompany”
(AESJ Investigation Committee) was organized at the AESJ General Assembly
heldonJune22,2012.WhenthecriticalityaccidentattheTokaiPlantofJCOCo.,
Ltdoccurredin1999,theAESJorganizedthe“AESJInvestigationCommitteeon
theJCOAccident”andconductedathoroughinvestigation.Followingthepractice
of this precedent, the AESJ has gathered representatives from all technical divi-
sions,relevantLiaisonMeetings/StandingCommittees,andtheBoardofDirectors
oftheAESJ,andhasactivelycarriedouttheinvestigation.
v
vi Preface
SincethefirstInvestigationCommitteeheldonAugust21,2012,theCommittee
hadconvened17meetingsbytheendof2013,basedontheinvestigationoutcomes
providedbytheSubcommittees,andtheseeffortshavenowcompiledintothisfinal
report.TheCommitteemembershopethatthisreportwillbeusedbytheexpertsas
well as by the public broadly and contribute to nuclear safety enhancement. It
wouldbeourgreatpleasureifthisreportinEnglishcouldprovidetheinsightofthe
accidenttotheinternationalsociety.
Tokyo,Japan SatoruTanaka
August 2014
Contents
1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 BackgroundtotheEstablishmentoftheAESJ
InvestigationCommittee. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 ActivitiesoftheAESJInvestigationCommittee. . . . . . . . . . . . . 2
1.3 StructureoftheReport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 OverviewofNuclearPowerStation. . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 OverviewofFacilitiesintheFukushimaDaiichi
NuclearPowerStation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 MainFacilitiesIncludingSafetyEquipment. . . . . . . . . . 7
2.1.2 FacilitiesforAccidentManagementMeasures. . . . . . . . 14
2.1.3 SeismicResistantDesignandTsunami
ResistantDesignforFacilities. . . . . . . . . . . . . . . . . . . . 15
2.2 OverviewofFacilitiesinthePowerStationsOther
ThantheFukushimaDaiichiNuclearPowerStation. . . . . . . . . . 17
2.2.1 TheFukushimaDainiNuclearPowerStation. . . . . . . . . 17
2.2.2 TheOnagawaNuclearPowerStation. . . . . . . . . . . . . . . 17
2.2.3 TheTokaiDainiNuclearPowerStation. . . . . . . . . . . . . 17
3 OverviewoftheAccidentattheFukushimaDaiichi
NuclearPowerStation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.1 DamageCausedbytheEarthquakeandTsunami. . . . . . . . . . . . 19
3.2 Unit1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.3 Unit2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.4 Unit3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.5 Unit4andSpentFuelPools. . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.6 Unit5andUnit6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
vii
viii Contents
4 OverviewofEventsOccurringatPowerStationsOther
ThantheFukushimaDaiichiNuclearPowerStation. . . . . . . . . . . . . 43
4.1 TheFukushimaDainiNuclearPowerStation. . . . . . . . . . . . . . . 43
4.1.1 OverviewoftheFukushimaDainiNuclear
PowerStation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.1.2 OverviewoftheEarthquakeandTsunami. . . . . . . . . . . 43
4.1.3 InfluenceoftheSeismicGroundMotion
andtheTsunami. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.1.4 ResponseBeforetheArrivaloftheTsunami. . . . . . . . . 46
4.1.5 ResponseAftertheArrivaloftheTsunami. . . . . . . . . . 46
4.2 TheOnagawaNuclearPowerStation. . . . . . . . . . . . . . . . . . . . . 50
4.2.1 OverviewoftheOnagawaNuclearPowerStation. . . . . 50
4.2.2 OverviewoftheEarthquakeandTsunami. . . . . . . . . . . 50
4.2.3 InfluenceoftheSeismicGroundMotion
andTsunami. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.2.4 ResponseBeforetheArrivaloftheTsunami. . . . . . . . . 53
4.2.5 ResponseAftertheArrivaloftheTsunami. . . . . . . . . . 54
4.2.6 TsunamiCountermeasuresBeforetheAccident. . . . . . . 55
4.3 TheTokaiDainiNuclearPowerStation. . . . . . . . . . . . . . . . . . . 57
4.3.1 OverviewoftheTokaiDainiNuclearPowerStation. . . . 57
4.3.2 OverviewoftheEarthquakeandTsunami. . . . . . . . . . . 57
4.3.3 InfluenceoftheSeismicGroundMotion
andTsunami. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.3.4 ResponseBeforetheArrivaloftheTsunami. . . . . . . . . 59
4.3.5 ResponseAftertheArrivaloftheTsunami. . . . . . . . . . 60
4.3.6 TsunamiCountermeasuresBeforetheAccident. . . . . . . 61
4.4 SummaryComparison. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5 Off-SiteResponse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.1 EmergencyResponsePlanPriortotheAccident. . . . . . . . . . . . . 71
5.2 OverviewofEmergencyActionsTakenintheEvent
oftheAccident. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.2.1 InitialResponseActionsDuringanEmergency. . . . . . . 72
5.2.2 UrgentProtectiveActionsforResidents
(Evacuation,etc.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.2.3 AdditionalEarlyProtectiveActions. . . . . . . . . . . . . . . . 76
5.2.4 TransitiontoLong-termProtectiveActions. . . . . . . . . . 77
5.3 IndividualIssuesofEmergencyActions. . . . . . . . . . . . . . . . . . . 78
5.3.1 Residents’Evacuation. . . . . . . . . . . .. . . . . . . . . . . . . . 78
5.3.2 StandardLimitsforRadionuclidesinFoods. . . . . . . . . . 83
5.3.3 RadiationandExposureDoseMeasurements. . . . . . . . . 87
5.3.4 EnvironmentalPollutionbyRadioactiveMaterial
andDecontamination. . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.4 RadioactiveMaterialReleaseandINESEvaluation. . . . . . . . . . . 104
5.4.1 EstimatedAmountofRadioactiveMaterialRelease. . . . 104
Contents ix
5.4.2 INESEvaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.5 CommunicationAftertheAccident. . . . . . . . . . . . . . . . . . . . . . 112
5.5.1 MiscommunicationRelatedtotheActorsInvolved. . . . . 113
5.5.2 CommunicationstothePublicbyAESJ. . . . . . . . . . . . . 114
5.6 Off-siteSupportActivities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
5.6.1 ActualConditionsoftheOff-siteDistribution. . . . . . . . 115
5.6.2 StatusofSecuringMaterialsandEquipment. . . . . . . . . 116
5.6.3 SecuringPowerSupplyVehicles. . . . . . . . . . . . . . . . . . 117
5.6.4 SecuringFireEngines. . . . . . . . . . . . . . . . . . . . . . . . . . 118
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6 AccidentAnalysisandIssues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.1 OverviewofAccidentAnalysis. . . . . . . . . . . . . . . . . . . . . . . . . 121
6.1.1 ItemsintheAnalysis. . . . . . . . . . . . . . . . . . . . . . . . . . 122
6.1.2 EvaluationofAccidentProgressionBehavior. . . . . . . . . 128
6.1.3 EvaluationofRadioactiveMaterialRelease. . . . . . . . . . 145
6.2 ConceptofNuclearSafety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6.2.1 BasicPrinciplesofNuclearSafety. . . . . . . . . . . . . . . . . 154
6.2.2 RiskAssessmentandUtilizationofRisk
Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
6.2.3 SafetyGoalsandRiskReduction. . . . . . . . . . . . . . . . . . 161
6.2.4 SafetyofNuclearPowerGeneration
andMechanismofEnsuringSafety. . . . . . . . . . . . . . . . 164
6.2.5 RelationshipBetweenNuclearSafety
andNuclearSecurity. . . . . . . . . . . . . . . . . . . . . . . . . . 167
6.3 DefenceinDepth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
6.3.1 DefenceinDepthPerceptioninJapan. . . . . . . . . . . . . . 171
6.3.2 AnalysisofDefenceinDepthintheLight
oftheFukushimaDaiichiNPSAccident. . . . . . . . . . . . 174
6.3.3 DefenceinDepthDeepeningandFutureSteps. . . . . . . . 178
6.4 PlantDesign. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
6.4.1 AnalysisonDesign. . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
6.4.2 SystemSafetyinPlantDesign. . . . . . . . . . . . . . . . . . . . 187
6.4.3 DiscussionPointsontheIsolationCondenser(IC). . . . . 195
6.4.4 MaterialsandStructuralIntegrity. . . . . . . . . . . . . . . . . 204
6.4.5 AgeingDegradation. . . . . . . . . . . . . . . . . . . . . . . . . . . 212
6.5 AccidentManagement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
6.5.1 RadioactiveMaterialContainmentFunction
ofPrimaryContainmentVessel. . . . . . . . . . . . . . . . . . . 216
6.5.2 ReactorInstrumentationSystems
(ReactorWaterLevelInstrumentation). . . . . . . . . . . . . 218
6.5.3 CoolantInjectionandHeatRemovalSystems. . . . . . . . 222
6.5.4 ImportanceofManagement. . . . . . . . . . . . . . . . . . . . . . 225
6.5.5 MultipleReactorsintheSameSite. . . . . . . . . . . . . . . . 231